The present invention is directed to a variable speed induced draft fan and motor for a gas furnace.
Induced draft blowers remove the corrosive waste gases remaining after combustion occurs within the heat exchange cells of a furnace. The induced draft blower induces a draft within the heat exchanger cell and then impels the gases through the blower and into a chimney, a vent or the like.
A constant speed draft inducer blower is susceptible to operational changes due to transient conditions. As an example, furnaces that are vented from the induced draft blower in a horizontal direction are susceptible to gusts of wind that blow into the vent pipe and cause a pressure change. This pressure change is sensed by a pressure switch which opens and shuts down the furnace.
Additionally, constant speed induced draft blowers are affected by the environment in which they are located. The length and diameter of the vent or chimney should be within desired ranges in order for a constant speed induced draft blower to operate properly. Additionally, the constant speed induced draft blower cannot compensate for changes or blockages in the vent or chimney.
Also, a constant speed induced draft blower cannot compensate for the environment in which it is installed. Installations at higher altitudes require a costly and time consuming high altitude retrofit kit.